Selena Gomez sings Britney Spears song in adorable childhood video

"The hustle was real," Gomez captioned her video.

Once a Britney Spears fan, always a Britney Spears fan: That's the message Selena Gomez sent to her Instagram followers after sharing a throwback video of herself passionately singing along to one of Spears' classics.

"The hustle was real," the star captioned the adorable, never-before-seen video.

The snippet shows an 8-year-old Gomez enthusiastically singing along to Spears' 2000 song, "Don't Go Knockin' on My Door."

In the video, Gomez is rocking blue-tinted sunglasses as she stands in front of a dramatic digital backdrop of storm clouds and cyclones.

As little Selena, who's now 28, sings, "You better get off my back/Don't go knockin' on my door," she rips off her sunglasses and stares down the camera.

Of course, the star's fans delighted in the surprise post, with Gomez's makeup company Rare Beauty commenting with crying/laughing emojis and declaring, "Too real."

Spears has yet to react to the video.

"Don't Go Knockin' on My Door" was released as part of Spears' sophomore album "Oops!... I Did It Again." The album was nominated for the 2001 Best Pop Vocal Album Grammy and went on to become one of the best-selling albums of all time, selling over 20 million copies.